@leocg I have enabled the flag and it works great, I have not encountered drawbacks yet, cannot wait for further developments, the idea that every item in the Sidebar has - and remembers - the size you have set it is great, way more practical than Vivaldi's panels, where everything is of the same size (example: a video player requires a different screen size than a dictionary).
I'd just like the option of setting Any search engine as my default and have it used when I highlight a word and the "Search/Copy" option comes up.
you can do that with an extension - I use context-search web extension - which I find way more practical since when you highlight a word you get a pop-up with all the search engines you have in the extension.
If you right-click on a tab, you can goto "save" and choose "all tabs as a speed dial folder". Then, you can later right-click on that folder and choose "open all in tabs" or choose to open all of then in a certain workspace.
In addition to that though, if you use ctrl + left-click to select multiple tabs, when you right-click on one of the selected tabs and goto "save", it'll say just "tabs as a speed dial folder" where it will just save the selected tabs to a speed dial folder.
You can also give those speed dial folders a name if you want. And, at the URL opera:/bookmarks, you can move the folders from the speed dial folder to somewhere else if you don't want them on the startup page.
@indigoxiv You can always use extensions like Leechblock or something similar to achieve such results. Although this feature is actually a deal breaker for me too since I happen to waste a lot of time surfing internet which I rather want to divert into my self growth. That's why I use Stay Focused app on Android to cut down my phone usage.